I have heard of it and know it is a table of all known elements, but what are elements, what do they mean, and how do they affect us?

Also i have heard that on the table there is a section that has spaces for i think 7 unknown elements. My question is how are people supposed to know an element is unknown when it hasnt been discovered?

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Common sense isn't so common

Chemistry and nuclear physics.

That is the answer to your question. The whole science of
chemistry, plus the whole of nuclear physics, is the only
real answer to your question.

Here are some tidbits -- entries I wrote for a glossary:

atom
Any of the tiny particles that ordinary matter is made of.
An atom is composed of a nucleus which contains one or more
protons and neutrons, surrounded by a cloud of electrons.
Protons are electrically positive, electrons negative.
Atoms hold together because the oppositely-charged particles
attract each other.

There are 100 or so different kinds of atoms, called elements.
Atoms often stick to each other, forming molecules. For example,
two hydrogen atoms stick to an oxygen atom, resulting in a
molecule of water.


chemistry
The study of atoms and how they join together into molecules.


electron
A fundamental particle, it is the lightest particle having a
measureable mass, and has a negative electric charge. One of
the three stable particles that atoms are made of. Electrons
flowing through your computer make it go. Electrons hitting
your monitor screen make it glow.


element
Any of the 100 or so kinds of atoms. Different elements are
distinguished by the number of protons they contain. Hydrogen
atoms each contain one proton, helium atoms each contain two
protons, lithium atoms each contain three protons, and so on.
The periodic table of elements organizes the elements by the
number of protons and by their chemical properties.

Atoms normally have equal numbers of protons and electrons, but
when ionized, or when combined with other atoms into molecules,
they may lose or gain electrons. When this happens, the atom
has an overall electric charge.

Atoms of a given element may also contain differing numbers of
neutrons. Most atoms have about equal numbers of protons and
neutrons, usually with a slightly greater number of neutrons.
Atoms with different numbers of neutrons are called isotopes.


ion
An electrically-charged atom or other particle. Normally, an
atom is electrically neutral, because the positive charge of the
proton(s) in the nucleus is balanced by the equal but opposite
negative charge of the electron(s) in the cloud surrounding the
nucleus. A neutral atom becomes ionized when it loses or gains
electrons. When it loses an electron, the atom takes on an
overall positive charge, and is called a cation. When it gains
an electron, it becomes a negatively charged anion.


isotope
An atom of a particular element which has a particular number of
neutrons in the nucleus. All atoms of a given element have the
same number of protons, but the number of neutrons can vary.
Atoms which have more neutrons are heavier, so different isotopes
of an element can be separated from each other by their different
densities, even though they have the same chemical properties.

Some isotopes are unstable, and thus radioactive. When an
unstable isotope decays, the atomic nucleus gives off high-energy
radiation, changing into a different isotope of the same element,
or into an isotope of a different element.

For example, carbon has six protons. Three isotopes of carbon
are C-12, which has six neutrons and is stable; C-13, which has
seven neutrons and is also stable; and C-14, which has eight
neutrons and is radioactive, with a half-life of 5760 years.
When Carbon-14 decays, the nucleus gives off a high-energy
electron, changing it into Nitrogen-14, a stable isotope with
seven protons and seven neutrons. Carbon-14 is used to date
organic remains from historic and pre-historic times. Almost
99% of all carbon atoms are C-12. Slightly over 1% are C-13.
The remaining isotopes, including C-14, constitute a vanishingly
tiny fraction of 1% of all carbon atoms.


neutron
A fundamental particle present in the nuclei of all atoms except
ordinary hydrogen. Neutrons are nearly identical to protons
except that they are electrically neutral (no electric charge),
and are slightly heavier. Neutrons in the nucleus of an atom are
stable. Outside a nucleus, neutrons have a mean lifetime of
about 13 minutes, and decay into a positively-charged proton, a
negatively-charged electron, and a neutral antineutrino.


nucleus
An atomic nucleus is the central part of an atom, consisting of
protons and neutrons. The nuclei of some atomic isotopes, such
as uranium 236, are unstable, and release energy when they break
down. Depending on the isotope, this energy may be in the form
of alpha particles (fast-moving helium nuclei), beta rays
(fast-moving electrons or positrons), gamma rays (high-energy
photons), or fast-moving nucleons (protons or neutrons). Each
of these has various uses in studying DNA or treating genetic
diseases. Since the energy comes from the atom's nucleus, it
is called "nuclear energy" and "nuclear radiation".

The protons and neutrons in an atomic nucleus are held together
by the strong nuclear force, which is strong enough to overcome
the electrical repulsion between protons.


periodic table
A chart showing how the physical and chemical properties of
different elements are related. Elements are listed in order
of number of protons. The most common arrangement puts the
first element, hydrogen, containing just one proton, at the
upper left. The second element, helium, then goes at the upper
right. The third element, lithium, has some properties which
are similar to the properties of hydrogen, so it begins a new
row, immediately underneath hydrogen. There are eight elements
in this row, ending with neon, which has properties similar to
those of helium. The third row begins with sodium, which has
properties similar to lithium.

http://www.freemars.org/jeff/elements/

The chemical properties of different elements are determinined
by the number and arrangement of electrons in the outermost
parts of their electron clouds. Each electron can have only a
specific amount of energy while inside the atom. This restricts
the electron to a particlar electron shell and orbital, which
has a particular energy level. In order to move from one
orbital to another, or to join or leave an atom entirely, an
electron must gain or lose energy.

The first row of the periodic table contains the two elements
which normally have their electrons in the first, lowest-energy
shell. This shell can only hold two electrons.

The second row of the table contains the eight elements which
normally have their outermost electrons in the second shell.
This shell can hold eight electrons.

An electron shell which is nearly full attracts electrons from
other nearby atoms, in order to complete the shell. For example,
hydrogen, with one electron, attaches to an oxygen atom in order
to grab an electron and fill its first shell. The oxygen, with
six electrons in its outermost shell, attaches to two hydrogen
atoms in order to fill that shell with eight electrons.

Electrons in a shell which has only one or two electrons in it
are held loosely, and are easily lost to other atoms. For
example, sodium, with one electron in its outermost (third)
shell, attaches to a chlorine atom in order to give the electron
to the chlorine. The sodium then has a full outermost (second)
shell containing eight electrons.

Elements such as sodium, which have only one or two loosely-held
electrons in the outermost shell, are found at the left and
center of the table, and are metals.

Elements such as oxygen and chlorine, which have nearly full
outermost electron shells and grab electrons from other atoms,
are found near the right end of the table, and are nonmetals.

Elements in the very last column on the right do not want to
gain or lose electrons at all, because their shells are filled,
so they don't form chemical bonds with other atoms. They are
the noble or inert gases. All noble gases except helium
normally have eight electrons in the outermost shell.

Hydrogen is unique among the elements because, with only a
single electron, it cannot give up that electron to result in a
filled outer shell. So hydrogen has some properties of metals,
and some properties of nonmetals.

The third row of the table contains the eight elements which
normally have their outermost electrons in the third shell.

In the fourth row of the table, the first two electrons go
into the fourth shell, but the next ten electrons go into the
third shell, which can hold 18 electrons. Elements in which
electrons are added to the next-to-outermost shell are called
transition metals. The outermost shell normally contains
either one or two electrons. When the third shell is full,
further electrons go into the outermost (fourth) shell, until
it contains eight electrons.


proton
One of the three fundamental, stable particles that atoms are
made of. Protons have positive electric charge, and are
located in the atomic nucleus. The simplest atom, hydrogen,
consists of a single proton and a single electron.

---------------------------------------------------------------

In my periodic table, I did not show the spaces for undiscovered
elements, or even the most-recently discovered unstable elements,
because they are not important for the purpose of the glossary.

Here's another link to the same table:

http://www.freemars.org/jeff/elements/

You can find tables with far more info on other websites. Mine
is mainly a quick and easy toy for memorizing the names, atomic
numbers, and positions of elements within the table.

-- Jeff, in Minneapolis

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http://www.FreeMars.org/jeff/

"The other planets?
Well, they just happen to be there, but the point of rockets is to explore them!"
-- Kai Yeves

woah thats a lot of info, ill read it thanx for the help

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Common sense isn't so common

There are many tables of elements: Chemogenesis: A Selection of Periodic Tables

Of course, the best is an Astronomers Periodic Table of the Elements, parsimoniously dividing the elements into 3 types -- Hydrogen, Helium, and the Metals.

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0 1 1 0 1 0 0 1 1 0 0 1 0 1 1 0 1 0 0 1 0 1 1 0 0 1 1 0 1 0 0 1 1 0 0 1 0 1 1 0 0 1 1 0 1 0 0 1 0 1 1 0 1 0 0 1 1 0 0 1 0 1 1 0....

A table can have entries for lots of unknown elements: Seaborg's Extended Periodic Table, with space for more than 100 unknowns.

If it wasn't clear from Jeff Root's material, atoms are made of bulding blocks -- electrons, protons and neutrons. We have studied the first, the smallest, 109 or so. Many more remain to be studied -- though they may have to be built first.

Edit: I'm so far behind. Up to 118, Ununoctium, in 1999, with number 117 yet to be produced.
Edit: Nope. Though 118 and 116 were claimed in 1999, the claim was retracted later. So, we're only up to 115 -- Ununpentium, reported 2004?

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0 1 1 0 1 0 0 1 1 0 0 1 0 1 1 0 1 0 0 1 0 1 1 0 0 1 1 0 1 0 0 1 1 0 0 1 0 1 1 0 0 1 1 0 1 0 0 1 0 1 1 0 1 0 0 1 1 0 0 1 0 1 1 0....

One question that immediately springs to mind in regards to the table is, is there any theoretical limit to the number of electrons, neutrons and protons you can stuff into an atom?

Has this question been answered with any semblance of certainty?

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BugMeNot A portal to bypass free-site registration.

"All truth passes through three stages. First, it is ridiculed, second it is violently opposed, and third, it is accepted as self-evident." Arthur Schopenhauer - renowned 19th Century German philosopher.

The limit is a moving target. It depends on the amount of energy you have available, and your ability to measure/verify small quantities in very short periods of time. All of the elements at the extreme upper end of the chart are extremely unstable.

I don't know. PhysOrg.web: Superheavy elements is a decent survey about what it took to get up to 118. Each few new elements required new methods of production to be invented. It seems a little like the quest to travel faster -- scientists get stuck for a while, hit a barrier, then someone finally comes up with a new method to make advances.

Perhaps a nuclear chemist, or merely someone better read than I -- not hard -- will chime in if there are any elements that are known to be unproduceable.

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0 1 1 0 1 0 0 1 1 0 0 1 0 1 1 0 1 0 0 1 0 1 1 0 0 1 1 0 1 0 0 1 1 0 0 1 0 1 1 0 0 1 1 0 1 0 0 1 0 1 1 0 1 0 0 1 1 0 0 1 0 1 1 0....

As far as the unknown elements, when Mendeleev first proposed this style of tabling the elements (19th century), he deliberately left open spots for elements he insisted would be discovered and would have properties that would fit into the empty spots in the table.

There was some derision when he first proposed this, but it faded when the next two element discoveries fit perfectly.

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Keeper of the Jabberwock

Whilst it's true the general picture is towards greater instability with increasing z, there are islands of stability where nuclear shells complete. There is supposed to be one around z=118, and there will be further islands much further along, with the next shell closures.

What's more the most stable isotopes of the heaviest elements have yet to be made. That's because no-one has managed to get enough neutrons into the product nucleus.

118 protons is a complete shell, but the number of neutrons really also needs ot be a complete shell for it to be really stable. As kzb says the biggest issue is that even when you manage to get two very neutron heavy isotopes of lower elements together, they still have way to few neutrons to complete the next shell, and to be the right number to hold the nucleus together.

That being said, there is also evidence that the largest nuclei aren't even spherical, meaning that some of the principles of the shell model stop being completely applicable.

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Forming opinions as we speak

Depends on how you define it. I belive anything above an atomic mass of around 208 is radioactive, so anything above that will eventually decay down to a mass of 208. Some radioactive elements have ridiculously long half lives. Thorium 232 has a half life of 14 billion years. As you get larger, the half lives tend to get shorter. Americium 243 lasts 7370 years, Californium 251 lasts 898 years, Seaborgium (element 106) 266 lasts 21 seconds.

the stability islands are a relative thing, and still pretty iffy. Element 116 may last minutes instead of seconds, but it will still decay pretty quick. Even if it has complete neutron shells, it will still alpha decay, just because the nucleus is not stable.